Black is based on the underground activities in the city of Kochi(Cochin). Shanmughan (Mammooty) plays a Head Police Constable but also a hitman who does his job with perfection. On the top of the underworld, there is a man, Advocate Devin Carlos Padaveedan (Lal). He and Shanmughan are accomplices. A newly appointed police officer, Ashok (Rahman), tries to clean up the city from the criminals, but fails to do so as he is killed by Padaveedan. Shanmugan is not very happy about the death of Ashok, and creates some indifference between the friends. After Shanmugan finds his own daughter, he wants to live a peaceful life, but the transformation is not acceptable to Padaveedan, and he wants Shanmughan dead. This changes the situation, and as Shanmughan asks City Police Commissioner (Babu Antony) for aiding him to kill the gangsters, he could only speak about putting them in jail. This leads to Shanmughan going against the criminals and eliminating them one by one. At the same time, Padaveedan is ready for the arrival of his old friend and current enemy.